Recommended bolt size for lead

L

Lucky_7

Member
Hey guys,

I need to bolt on some lead pucks, about 3 lbs a piece, and I am wondering if 1/4-20 bolt would be strong enough. From what I know, a s.s. 1/4-20 bolt should have tensile strength of 55,000 psi. But, I'd like to know what you guys use, or have had experience with. I could go with 5/16-18, but I'd lose a little more weight off the puck when I drill it.
 
Throw a fishing weight in your pocket, and drll 5/16.

Lol

Not a real large split shot, even.
Lead weighs 0.409 lbs per cu inch

3 lb weight, 1.5 inch thick.
1/4 inch hole = .250 times .250 times .7854 times 1.5 times .409 equals 0.0301 lbs
5/16 inch hole = .312 times .312 times .7854 times 1.5 times .409 equals 0.0469 lbs.

Now the bolt and nut weigh more. Difference gets even smaller.
 
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5/16 is probably most common and would be ok for that size weight. I use 3/8 but I'm hanging larger weight. Just be sure to double nut, paint white and put your name on them and if you aren't changing weight maybe even lock nut them.
 
SCKarter2 said:
5/16 is probably most common and would be ok for that size weight. I use 3/8 but I'm hanging larger weight. Just be sure to double nut, paint white and put your name on them and if you aren't changing weight maybe even lock nut them.
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Better check the rules at the track, here all weight has to be on 5/16 min. And has to have locknuts.
Painted white and kart#
 
Lucky_7 said:
Hey guys,

I need to bolt on some lead pucks, about 3 lbs a piece, and I am wondering if 1/4-20 bolt would be strong enough. From what I know, a s.s. 1/4-20 bolt should have tensile strength of 55,000 psi. But, I'd like to know what you guys use, or have had experience with. I could go with 5/16-18, but I'd lose a little more weight off the puck when I drill it.
Click to expand...

Do yourself and your fellow racers a favor and use a 5/16 bolt and nut ! Most all tracks I ever raced required it as a minimum size and had to be either double nutted or if a single nut , it had to be drilled and pinned . Also they had to be painted white with your kart number on it . When it comes to the weights you should think safety first , last , and always !!!!!
 
ohv60racr said:
Do yourself and your fellow racers a favor and use a 5/16 bolt and nut ! Most all tracks I ever raced required it as a minimum size and had to be either double nutted or if a single nut , it had to be drilled and pinned . Also they had to be painted white with your kart number on it . When it comes to the weights you should think safety first , last , and always !!!!!
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Seen a kart kit one on the track, just missed a group of karts, hit a wood plank on the fence and knock a huge chunk out.
Lead is the most dangerous thing we bolt on the kart
 
XXX#40 said:
Better check the rules at the track, here all weight has to be on 5/16 min. And has to have locknuts.
Painted white and kart#
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Same at the tracks around here. That set of requirements seems to be getting pretty universal.
DO NOT use 1/4-20. 5/16" or more is cheap insurance.
 
Thanks guys, I far as I know, there is no track rule. But Ill ask. I will go get some 5/16s, thanks for all the advice. Glad I asked!
 
5/16 minimum , after seeing a friend lose a wka triple crown due to a 5/16 bolt failure.
I went to 3/8.
SS would be a disaster it Gauls up so easily , i believe you would be totally disappointed with it.
 
All weights added to the kart must be securely fastened to the kart with a minimum 5/16-inch diameter bolt. Any single weight weighing in excess of seven pounds shall utilize a minimum of two 5/16-inch diameter bolts or a single 3/8-inch diameter grade 5 bolt.

We use grade 5, 3/8" bolts. It's not worth the cheaper bolts, knowing you're taking a chance at hurling a 5 lb lead weight at someone over 100 mph.
 
If bolting weight to weight tabs welded to the frame be very careful about exceeding their capabilities. I have seen tabs break off lots of times with the lead still attached.
 
johnelliott said:
If bolting weight to weight tabs welded to the frame be very careful about exceeding their capabilities. I have seen tabs break off lots of times with the lead still attached.
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Many new chassis don't even come with weight tabs, we never used them always to the seat or floor pan
 
I am aware that the newer chassis do not have weight tabs---there are still lots of older chassis around that do have tabs---just pointing that out.
 
I have an older phantom stalker and it still has the tabs, but I cannot use them because they are not in the right spots on the chassis for the weight. The bolts I got are 5/16, with lock washers and nylon insert nuts so I make double sure they shouldn't loosen, I also made sure to not over tighten them as to not weaken the bolt, but they are very secure.
 
Who ever came up with 2 bolts in the area of normal size puck should re-think that one, talk about weakening the area of the seat bolts go. I've see plenty weights come off but never because of the bolt breaking, tabs breaking off yes quite often seat breaking out yes as well.
 
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